1. Field of the Invention
The present invention generally relates to a diagnostic method for determining whether an electric drive assembly is producing a desired amount of torque and to an electric drive assembly which incorporates the method and more particularly, to an electric drive assembly which compares a pair of signals or values in order to determine whether the assembly is producing a desired amount of torque.
2. Background of the Invention
Electric drive assemblies are utilized in a wide variety of applications requiring the selective production of torque. Examples of such applications include, but are not limited to, manufacturing or producing an item or causing selective propulsion. It is desirable to ensure or ascertain whether these electric drive assemblies are desirably providing a required amount of torque.
One strategy to increase the likelihood that a desired amount of torque will be produced by an electric drive assembly includes the use of an electrical current regulator which receives a measured signal which was previously communicated to the electric machine or torque producer and which represents the torque requested of the electric machine. Particularly, the current regulator subtracts this received signal from a second signal which represents the currently desired or commanded torque. The regulator uses this difference or modifier to produce a voltage signal which is used to create a torque control signal which is communicated to the electric machine, effective to cause the electric machine to produce the certain amount of desired torque. The current regulator therefore tends to cause the electric machine to produce a desired amount of torque.
While this strategy does reduce the likelihood of the production of undesired torque, it does not entirely eliminate the possibility of undesired operation. This strategy also does not ensure that such undesired operation will be recognized in a timely manner by an operator or user of the electric drive assembly since the electrical current regulator does not identify, or make known to the user, the nature of the operation of the electric drive assembly.
The present invention allows for a relatively efficient determination to be made of the amount of torque which is produced by an electric drive assembly and for the selective creation of a positive indication or diagnostic feedback signal which is indicative of the operational status of the electric drive assembly, thereby allowing an operator or a user of the electric drive assembly to take some action in the event that the electric drive assembly is producing an undesirable amount of torque.